fabric@lists.hyperledger.org | anyone able to iterate over records using getStateByRange?

Siddharth Jain

#7646

this method:

https://fabric-shim.github.io/master/fabric-shim.ChaincodeStub.html#getStateByRange

Note that startKey and endKey can be empty string, which implies unbounded range query on start or end.

is supposed to enable enumerating records in the database but when we tried it, it did not work. e.g.:

public async getAssets(ctx:
Context): Promise<Asset[]> {
        const assets:
Asset[] = [];
        const results =
await ctx.stub.getStateByRange('',
'');
        while (true) {

            let item =
await results.next();
            if (item.done) {
                break;
            } else {
                let buffer =
item.value.getValue();
                let asset =
JSON.parse(buffer.buffer.toString())
as Asset;     // buffer.buffer returns many records not just once and the JSON.parse will fail           

                assets.push(asset);                
            }
        }
        await results.close();
        return assets;
    }

buffer.toString()

"ByteBufferNB(offset=22,markedOffset=-1,limit=386,capacity=1981)"

buffer.buffer.toString()

"

�

mycc00000�{"createdBy":"","id":"00000","lastModifiedBy":"","metadata":"","owner":"org2MSP"}

�

mycc00001�{"createdBy":"","id":"00001","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

mycc00002�{"createdBy":"","id":"00002","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

mycc00003�{"createdBy":"","id":"00003","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

mycc00004�{"createdBy":"","id":"00004","lastModifiedBy":"","metadata":"","owner":"org1MSP"}$efc8d188-16ae-41e8-a024-7880a8d0bf31"

JSON.parse(buffer.buffer.toString())

SyntaxError: Unexpected token � in JSON at position 1

buffer.buffer.buffer.toString()

"[object ArrayBuffer]"

has anyone been able to use this method successfully?

Matthew White

#7659

Hello;

Check the API docs here https://hyperledger.github.io/fabric-chaincode-node/release-1.4/api/tutorial-using-iterators.html

Will need to double check, but as a workaround for an unbounded range try this as the end key

const MAX_UNICODE_RUNE_VALUE = '\u{10ffff}';

Though such an unbounded range could potentially give you a lot data; worth looking at the pagination variants especially if there's any doubt about the size of data that might come back

Regards, Matthew.

Matthew B White IBM Blockchain Solutions Architect

Email me at WHITEMAT@...

Find me on StackOverflow, and generally at calanais.me.uk

Note: restricted availability for meetings 14:30 to 17:00 UK Tuesday

IBM United Kingdom Limited, Hursley Park, Winchester, Hampshire, SO21 2JN

"The wrong answers are the ones you go looking for when the right answers stare you in the face"

----- Original message -----
From: "Siddharth Jain" <siddjain@...>
Sent by: fabric@...
To: "fabric@..." <fabric@...>
Cc:
Subject: [EXTERNAL] [Hyperledger Fabric] anyone able to iterate over records using getStateByRange?
Date: Wed, Jan 29, 2020 9:24 PM

this method:

https://fabric-shim.github.io/master/fabric-shim.ChaincodeStub.html#getStateByRange

Note that startKey and endKey can be empty string, which implies unbounded range query on start or end.

is supposed to enable enumerating records in the database but when we tried it, it did not work. e.g.:

public async getAssets(ctx: Context): Promise<Asset[]> {

const assets: Asset[] = [];

const results = await ctx.stub.getStateByRange('', '');

  while (true) {

let item = await results.next();

if (item.done) {

break;

} else {

let buffer = item.value.getValue();

  let asset = JSON.parse(buffer.buffer.toString()) as Asset; // buffer.buffer returns many records not just once and the JSON.parse will fail

      assets.push(asset);

}

}

await results.close();

return assets;

}

buffer.toString()
"ByteBufferNB(offset=22,markedOffset=-1,limit=386,capacity=1981)"

buffer.buffer.toString()

"

�

�

mycc00000�{"createdBy":"","id":"00000","lastModifiedBy":"","metadata":"","owner":"org2MSP"}

�

�

mycc00001�{"createdBy":"","id":"00001","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

�

mycc00002�{"createdBy":"","id":"00002","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

�

mycc00003�{"createdBy":"","id":"00003","lastModifiedBy":"","metadata":"","owner":"org1MSP"}

�

�

mycc00004�{"createdBy":"","id":"00004","lastModifiedBy":"","metadata":"","owner":"org1MSP"}$efc8d188-16ae-41e8-a024-7880a8d0bf31"

JSON.parse(buffer.buffer.toString())

SyntaxError: Unexpected token � in JSON at position 1

buffer.buffer.buffer.toString()

"[object ArrayBuffer]"

has anyone been able to use this method successfully?

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